JP-A-11-139225 discloses a tunnel detecting device for a vehicle that detects a tunnel by using an image pickup device. According to this tunnel detecting device, a white line is recognized, and an area in which the vehicle concerned will travel is searched to extract an area having a predetermined concentration. Furthermore, a noted area (low luminance area) indicating the entrance or exit of a tunnel is detected, and the height or area thereof is calculated, thereby detecting the tunnel.
An elevated bridge tends to be misidentified as a tunnel in a tunnel detecting technique for vehicles, and particularly in the case of use of a vehicle light control system, unnecessary instantaneous lighting occurs when a vehicle passes below an elevated bridge in the daytime. If unnecessary instantaneous lighting under the state that a vehicle passes below an elevated bridge is required to be prevented according to the technique of the above publication, it induces complexity of logic.